Changes in ghrelin mRNA level, plasma growth hormone concentration and performance in different dietary energy and protein levels in broiler chicken

Abstract

We studied the effects of different energy and protein contents of the diet on performance, growth hormone concentration and ghrelin gene expression in broiler chicken. Two experiments were conducted to determine whether different dietary energy and protein levels alter growth hormone concentration and ghrelin mRNA abundance in broiler chicks. Body weight and feed intake were recorded weekly. Blood, carcass traits and proventriculus samples were collected at 21, 42 and 56 days of age. Blood samples assayed for growth hormone (GH) concentration by radio immuno assay (RIA) and ghrelin gene expression from proventriculus tissue was measured by Real Time polymerase chain reaction (PCR). Feed intake and body weight gain increased in broilers fed on low-energy diets compared with those fed on high-energy diets at 21 days of age (P<0.0001). Also, increasing dietary energy improved feed conversion (FCR) at 22–42 days of age in broiler chicken (P<0.0001). Increasing levels of protein increased feed intake, body weight gain and improved FCR as compared with low level of protein. Carcass percentage and breast percentage increased in broilers fed on high protein diets compared with those fed on low-protein diets during different periods. High-energy and low-protein diets increased abdominal fat percentage in broiler chickens. The result of this experiment indicated that there was no effect of different dietary energy and protein levels on growth hormone concentration and ghrelin gene mRNA expression for broiler chicken.